added optional coefficient of thrust curve input to cmod_windpower fo…

…r the park wake model. placeholder for functionality of using the input needs to be updated.

shared/lib_windwakemodel.cpp

@@ -214,6 +214,13 @@ double parkWakeModel::delta_V_Park(double Uo, double Ui, double distCrosswind, d
 	// bound the coeff of thrust
 	double Ct = max_of(min_of(0.999, dThrustCoeff), minThrustCoeff);
 
+    // overwrite the coefficient of thrust if it has been specified by the user
+    // if it has not been specified by the user, the thrust curve vector is {0.}
+    if (ctCurve.size() != 1)
+    {
+        // do something here
+    }
+
 	double k = wakeDecayConstant;
 
 	double dRadiusOfWake = dRadiusUpstream + (k * distDownwind); // radius of circle formed by wake from upwind rotor

shared/lib_windwakemodel.h

@@ -153,12 +153,16 @@ class parkWakeModel : public wakeModelBase{
 	double rotorDiameter;
 	double wakeDecayConstant = 0.07,
 		   minThrustCoeff = 0.02;
+    std::vector<double> ctCurve; //vector that stores the optional coefficient of thrust curve input
 	double delta_V_Park(double dVelFreeStream, double dVelUpwind, double dDistCrossWind, double dDistDownWind, double dRadiusUpstream, double dRadiusDownstream, double dThrustCoeff);
 	double circle_overlap(double dist_center_to_center, double rad1, double rad2);
 
 public:
 	parkWakeModel(){ nTurbines = 0; }
-    parkWakeModel(size_t numberOfTurbinesInFarm, windTurbine* wt, double wdc) { nTurbines = numberOfTurbinesInFarm; wTurbine = wt; setWakeDecayConstant(wdc); }
+    parkWakeModel(size_t numberOfTurbinesInFarm, windTurbine* wt, double wdc, std::vector<double> ctc)
+    {
+        nTurbines = numberOfTurbinesInFarm; wTurbine = wt; setWakeDecayConstant(wdc); ctCurve = ctc;
+    }
 	virtual ~parkWakeModel() {};
 	std::string getModelName() override { return "Park"; }
 	void setRotorDiameter(double d){ rotorDiameter = d; }

ssc/cmod_windpower.cpp

@@ -72,7 +72,9 @@ static var_info _cm_vtab_windpower[] = {
 	{ SSC_INPUT  , SSC_NUMBER , "icing_cutoff_temp"                  , "Icing Cutoff Temperature"                 , "C"       ,""                                    , "Losses"                               , "en_icing_cutoff=1"                               , ""                                                , "" } ,
 	{ SSC_INPUT  , SSC_NUMBER , "icing_cutoff_rh"                    , "Icing Cutoff Relative Humidity"           , "%"       ,"'rh' required in wind_resource_data" , "Losses"                               , "en_icing_cutoff=1"                               , "MIN=0"                                           , "" } ,
 
+    // optional SDK only wake loss inputs
     { SSC_INPUT  , SSC_NUMBER , "wake_loss_multiplier"               , "Multiplier for the calculated wake loss"  , ""        ,">1 increases loss, <1 decreases loss", "Farm"                                 , ""                                                , "MIN=0"                                           , "" } ,
+    { SSC_INOUT  , SSC_ARRAY  , "wind_turbine_ct_curve"              , "Park model coeff of thrust curve vs WS"   , ""        ,"uses same wind speeds as power curve", "Turbine"                              , ""                                                , "LENGTH_EQUAL=wind_turbine_powercurve_windspeeds" , "GROUP=WTPCD" } ,
 
     { SSC_INPUT  , SSC_NUMBER , "wake_int_loss"                      , "Constant Wake Model, internal wake loss"  , "%"       ,""                                    , "Losses"                               , "wind_farm_wake_model=3"                          , "MIN=0,MAX=100"                                   , "" } ,
     { SSC_INPUT  , SSC_NUMBER , "wake_ext_loss"                      , "External Wake loss"                       , "%"       ,""                                    , "Losses"                               , "?=0"                                             , "MIN=0,MAX=100"                                   , "" } ,
@@ -291,7 +293,7 @@ void cm_windpower::exec()
 	wt.rotorDiameter = as_double("wind_turbine_rotor_diameter");
 	ssc_number_t *pc_w = as_array("wind_turbine_powercurve_windspeeds", &wt.powerCurveArrayLength);
     if (wt.powerCurveArrayLength == 1)
-        throw exec_error("windpower", util::format("The wind turbine power curves has insufficient data. Consider changing the turbine design parameters"));
+        throw exec_error("windpower", util::format("The wind turbine power curve has insufficient data. Consider changing the turbine design parameters"));
 	ssc_number_t *pc_p = as_array("wind_turbine_powercurve_powerout", NULL);
 	std::vector<double> windSpeeds(wt.powerCurveArrayLength), powerOutput(wt.powerCurveArrayLength);
 	for (size_t i = 0; i < wt.powerCurveArrayLength; i++){
@@ -404,10 +406,26 @@ void cm_windpower::exec()
         wakeModel = std::make_shared<simpleWakeModel>(simpleWakeModel(wpc.nTurbines, &wt));
     else if (wakeModelChoice == PARK)
     {
+        // get optional thrust curve
+        std::vector<double> ct_curve = { 0. }; //initialize this to length 1: a power curve length of 1 throws an exec error above & the length of ct curve is tied to the power curve, so this is a safe null value
+        if (is_assigned("wind_turbine_ct_curve"))
+        {
+            size_t *ctCurveLength = 0;
+            ssc_number_t *ctc = as_array("wind_turbine_ct_curve", ctCurveLength);
+            if (*ctCurveLength != wt.powerCurveArrayLength)
+                throw exec_error("windpower", "Thrust curve must have same number of values as the power curve");
+            ct_curve.resize(*ctCurveLength);
+            for (size_t i = 0; i < *ctCurveLength; i++)
+                ct_curve[i] = ctc[i];
+        }
+
+        // get optional wake decay constant
         double wdc = 0.07; //this is the default value
         if (is_assigned("park_wake_decay_constant"))
             wdc = as_double("park_wake_decay_constant");
-        wakeModel = std::make_shared<parkWakeModel>(parkWakeModel(wpc.nTurbines, &wt, wdc));
+
+        // create the wake model
+        wakeModel = std::make_shared<parkWakeModel>(parkWakeModel(wpc.nTurbines, &wt, wdc, ct_curve));
     }
     else if (wakeModelChoice == EDDYVISCOSITY)
     {

test/shared_test/lib_windwakemodel_test.h

@@ -154,7 +154,7 @@ class parkWakeModelTest : public ::testing::Test{
 		windSpeed.resize(numberTurbines);
 		turbIntensity.resize(numberTurbines, 0.1);
 		createDefaultTurbine(&wt);
-		pm = parkWakeModel(numberTurbines, &wt, 0.07);
+        pm = parkWakeModel(numberTurbines, &wt, 0.07, { 0. }); //use default values for the last two inputs
 		for (int i = 0; i < numberTurbines; i++){
 			windSpeed[i] = 10.;
 		}